Usage for the embbeded fingerprint reader in smartphones

This year I decided to get myself a new mobile phone. I am currently hesitating between the new iPhone and the latest Samsung flagships. I heard that both these devices possess fingerprint scanners. It can be used for unlocking the mobile phone and it is specific to the user. I was wondering what the other application of this technology are. I read online that these scanners can be used to validate payments online or authenticate access on certain sites. Can anyone elaborate?
